Process intensification in flotation using ultrasound
The application of ultrasound to improve the separation of mineral particles in flotation processes has received a growing interest in the past decade. However, the understanding of the underlying mechanism is far from being complete. Among the most favored hypotheses are: (i) increase of hydrophobicity of the particles by nucleation of nano- and microbubbles via cavitation and (ii) the stimulation of bubble oscillations which increase the collision efficiency with the particles.
We study bubble-particle attachment/detachment in small columns equipped with ultrasound transducers (ranging from 20 to 50 KHz), optics and a high speed camera. Different types of particles, e.g., organic substances, glass beads, plastics, minerals are used. We analyse the efficiency of attachment depending on ultrasound power, irradiation time, surface tension, viscosity, pH value and the concentration of particles. Primary focus is also to understand the flow field around the bubbles during ultrasound application.
The works are performed in collaboration with the groups of Prof. Lev Fillipov (University of Lorraine, Nancy) and Prof. Tatyana Lyubimova (Perm State University, Russia).